Abstracts

Rationale: Focal cortical dysplasia (FCD) is the most common cause of medically refractory epilepsy which often requires surgical intervention. Complete FCD resection of epileptogenic area is the most significant predictor of overall seizure outcome. We looked at our FCD resection comparing the use intraoperative MRI (iMRI) and conventional surgical techniques and looked at findings and surgical outcomes. Methods: This is a retrospective study in children who underwent resection of FCD at Children’s National Medical Center from January 2014 to Sep 2017 with at least 6 months follow up post op. Our database was queried for demographics, iMRI, location of FCD, pathology, Engel outcome, morbidity and complications.  Results: A total of 42 patients underwent FCD resection at our center. Twenty seven underwent resection assisted with iMRI, and 15 underwent conventional surgical techniques. Age of seizure onset ranged from 5 weeks to 14.2 years in the iMRI group and 2 months to 16 years in the conventional group with a mean duration of seizures of 71.6 months and 101 months, respectively.  The most common location of FCD in iMRI group was frontal and in conventional group was temporal. Twelve patients in iMRI group had FCD on an eloquent area whereas 3 patients in conventional group had dysplasia on an eloquent area.  FCD type IIa was the most common pathology in both groups. Post resection complications included transient extremity weakness (5), transient hallucinations (1) and transient sensory issue (1) in iMRI group. Transient weakness (1) and blurred vision (1) were seen in the conventional groupFor the iMRI group, twenty out of 27 (74%) had Engel 1 outcome. Of these, 5 had previous surgery. Thirteen had an apparent total gross resection of the FCD on iMRI. For 7 patients, the iMRI revealed residual dysplasia and five patients underwent further resection during the surgery. Seven patients had residual dysplasia versus postoperative changes on follow- up MRI.  Engel 3 outcome was seen in 2 cases (7%) due to the FCD being in an eloquent area or in a deep area. For the conventional group, 7 out of 15 (46.7%) had Engel 1 outcome. One patient had previous surgery. Six had no residual FCD in MRI and one patient had unclear postoperative change or residual dysplasia on the follow up MRI. Engel outcome 3 was 5 out 15 (33%). Conclusions: The use of iMRI assisted resection allows in majority, for complete resection of FCD and improves seizure outcome when compared with conventional resection. The near real time complete resection provided by iMRI is an advantage. However, the complete resection of FCD and post-operative complications also depends on the location of FCD (in an eloquent cortex or in a deep area).  Funding: None